Role of nitric oxide and KATP channel in the protective effect mediated by nicorandil in bile duct ligation-induced liver fibrosis in rats

Effect of Perioperative Nicorandil on Myocardial Protection in Patients Undergoing Cardiac Surgery with Cardiopulmonary Bypass, a Retrospective Study

Background

The potential myocardial protective effect of nicorandil (NICD) in patients undergoing percutaneous coronary intervention has been established. However, its efficacy in the context of cardiac surgery remains controversial. The present study aimed to evaluate the myocardial protective effect of perioperative NICD use in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB).

Methods

We retrospectively gathered data from patients undergoing cardiac bypass surgery between 12/2018 and 04/2021 in Fuwai Hospital. Subsequently, the patients were divided into two groups, NICD group and non-nicorandil (non-NICD) group. A 1, 3 propensity score matching (PSM) was conducted. The primary outcome was the incidence of myocardial injury. The secondary outcomes included the mechanical ventilation (MV) duration, intensive care unit (ICU) length of stay (LOS), hospital LOS, duration of chest drainage, the drainage volume, the total cost, the incidence of acute kidney injury (AKI), and the incidence of acute liver injury (ALI). Subsequently, we divided the entire population into two distinct subgroups based on their administration of NICD, and performed a comprehensive subgroup analysis.

Results

A total of 2406 patients were ultimately included in the study. After PSM, 250 patients in NICD group and 750 patients in non-NICD group were included in the analysis. Perioperative NICD reduced the incidence of myocardial injury (47.2% versus 38.8%, P=0.025). Our subgroup analysis revealed that preoperative NICD administration not only provided myocardial protection benefits (45.7% vs 35.8%, OR 0.66, 95% CI [0.45-0.97], P=0.041), but also demonstrated statistically significant reduction in ALI, the ICU and hospital LOS, and the duration of chest drainage (all P<0.05).

Conclusion

The perioperative NICD administration may confer myocardial protection in patients undergoing cardiac surgery with CPB. Furthermore, the preoperative utilization of NICD has the potential to mitigate the incidence of postoperative ALI, a reduction in the ICU and hospital LOS, and the duration of chest drainage.

Exploring the role of ATP-sensitive potassium channel, eNOS, and P-glycoprotein in mediating the hepatoprotective activity of nicorandil in methotrexate-induced liver injury in rats

BACKGROUND

Methotrexate (MTX) is a commonly used chemotherapeutic agent; however, its clinical use is challenged by various types of injuries, including hepatotoxic side effects. Therefore, finding new protective drugs against MTX-induced toxicities is a critical need. Moreover, the different mechanisms mediating such effects are still not clear. The current study aimed to evaluate the possible ameliorative action of nicorandil (NIC) in MTX-induced hepatotoxicity and examine the roles of the ATP-sensitive potassium channel (KATP), endothelial nitric oxide synthase (eNOS), and P-glycoprotein (P-gp).

MATERIALS AND METHODS

Thirty-six male Wistar albino rats were used. NIC (3 mg/kg/day) was given orally for 2 weeks, and hepatotoxicity was induced by a single intraperitoneal injection of MTX (20 mg/kg) on the 11th day of the experiment. We confirmed the role of KATP by co-administering glimepiride (GP) (10 mg/kg/day) 30 min before NIC. The measured serum biomarkers were [alanine transaminase (ALT) and aspartate transaminase (AST)], total antioxidant capacity (TAC), malondialdehyde (MDA), nitric oxide (NOx), tumor necrosis factor-alpha (TNFα), superoxide dismutase (SOD), and P-gp. Histopathology, eNOS, and caspase-3 immunoexpression were evaluated.

RESULTS

The MTX group displayed hepatotoxicity in the form of elevations of ALT, AST, MDA, NOx, and caspase-3 immunoexpression. Furthermore, the histopathological examination showed marked liver injury. TAC, SOD, P-gp, and eNOS immunoexpression showed significant inhibition. In the protective group, all parameters improved (P value < 0.05).

CONCLUSION

NIC has an ameliorative action against MTX-induced hepatotoxicity, most probably via its antioxidant, anti-inflammatory, and anti-apoptotic functions together with the modulation of the KATP channel, eNOS, and P-glycoprotein.

Nicorandil/ morphine crosstalk accounts for antinociception and hepatoprotection in hepatic fibrosis in rats: Distinct roles of opioid/cGMP and NO/KATP pathways

Previous report indicated that nicorandil potentiated morphine antinociception and attenuated hepatic injury in liver fibrotic rats. Herein, the underlying mechanisms of nicorandil/morphine interaction were investigated using pharmacological, biochemical, histopathological, and molecular docking studies. Male Wistar rats were injected intraperitoneally (i.p.) with carbon tetrachloride (CCl4, 40%, 2 ml/kg) twice weekly for 5 weeks to induce hepatic fibrosis. Nicorandil (15 mg/kg/day) was administered per os (p.o.) for 14 days in presence of the blockers; glibenclamide (KATP channel blocker, 5 mg/kg, p.o.), L-NG-nitro-arginine methyl ester (L-NAME, nitric oxide synthase inhibitor, 15 mg/kg, p.o.), methylene blue (MB, guanylyl cyclase inhibitor, 2 mg/kg, i.p.) and naltrexone (opioid antagonist, 20 mg/kg, i.p.). At the end of the 5th week, analgesia was evaluated using tail flick and formalin tests along with biochemical determinations of liver function tests, oxidative stress markers and histopathological examination of liver tissues. Naltrexone and MB inhibited the antinociceptive activity of the combination. Furthermore, combined nicorandil/morphine regimen attenuated the release of endogenous peptides. Docking studies revealed a possible interaction of nicorandil on µ, κ and δ opioid receptors. Nicorandil/morphine combination protected against liver damage as evident by decreased liver enzymes, liver index, hyaluronic acid, lipid peroxidation, fibrotic insults, and increased superoxide dismutase activity. Nicorandil/morphine hepatoprotection and antioxidant activity were inhibited by glibenclamide and L-NAME but not by naltrexone or MB. These findings implicate opioid activation/cGMP versus NO/KATP channels in the augmented antinociception, and hepatoprotection, respectively, of the combined therapy and implicate provoked cross talk by nicorandil and morphine on opioid receptors and cGMP signaling pathway. That said, nicorandil/morphine combination provides a potential multitargeted therapy to alleviate pain and preserve liver function.

Nicorandil reduces morphine withdrawal symptoms, potentiates morphine antinociception, and ameliorates liver fibrosis in rats

AIMS

Chronic liver disease (CLD) is a serious medical condition affecting patients globally and pain management poses a unique challenge. ATP-sensitive potassium channels (K_ATP) are expressed in nociceptive neurons and hepatic cells. We tested the hypothesis whether morphine and nicorandil, K_ATP channel opener, alone and in combination possess hepatoprotective, antinociceptive effect and alter morphine physical dependence.

MAIN METHODS

Intraperitoneal injection (i.p.) of carbon tetrachloride (CCl₄) induced liver fibrosis in male Wistar rats. Nicorandil (15 mg/kg/day) was administered per os for two weeks. Morphine (3.8, 5, 10 mg/kg, i.p.) was administered prior to antinociception testing in tail flick and formalin tests. Morphine physical dependence following naloxone injection, fibrotic, oxidative stress markers, and liver histopathology were assessed.

KEY FINDINGS

Morphine alone, produced insignificant changes of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), hyaluronic acid (HA), hepatic hydroxyproline (Hyp), malondialdehyde (MDA), and superoxide dismutase (SOD) levels and exerted significant antinociception in the pain models. Nicorandil alone protected against liver damage (decreased serum ALT, AST, HA, hepatic Hyp, MDA, increased SOD levels, improved fibrosis scores). Nicorandil/morphine combination produced remarkable hepatoprotection and persistent analgesia compared to morphine alone as evidenced by reduced (EC50) of morphine. Nicorandil augmented morphine analgesia and markedly decreased withdrawal signs in morphine-dependent rats.

SIGNIFICANCE

The data showed for the first time, the hepatoprotection and augmented antinociception mediated by nicorandil/morphine combination in liver fibrosis via antioxidant and antifibrotic mechanisms. Nicorandil ameliorated withdrawal signs in morphine dependence in CLD. Thus, combining nicorandil/morphine provides a novel treatment strategy to ameliorate hepatic injury, potentiate antinociception and overcome morphine-induced physical dependence in liver fibrosis.

Benincasa hispida extracts positively regulated high salt-induced hypertension in Dahl salt-sensitive rats: Impact on biochemical profile and metabolic patterns

Salt-induced hypertension is one of the major issues worldwide and one of the main factors involved in heart and kidney failure. The objective of this study was to investigate the potential role of Benincasa hispida extracts on high salt-induced hypertension in Dahl-salt sensitive (D-SS) rats and to find out the metabolic and biochemical pattern involved in the reduction of hypertension. Twenty-six Dahl salt-sensitive (D-SS) rats were selected and divided into four groups. The metabolic strategy was applied to test the extracts on salt-sensitive hypertension in kidney. Gas Chromatography-Mass spectrometry (GC-MS) was used to identify the potent biochemical profile in renal medulla and cortex of rat kidneys. The differential metabolites of cortex and medulla, enrichment analysis and pathway analysis were performed using metabolomics data. The GC-MS data revealed that 24 different antihypertensive metabolites was detected in renal cortex, while 16 were detected in renal medulla between different groups. The significantly metabolic pathways namely citrate cycle, glutathione metabolism, glycine, serine, and threonine metabolism, glyoxylate and dicarboxylate metabolism, glycerolipid metabolism, alanine, aspartate and glutamate metabolism in renal cortex and glycerolipid metabolism, pentose phosphate pathway, citrate cycle, glycolysis, glycerophospholipid metabolism, phenylalanine, tyrosine and tryptophan biosynthesis in renal medulla were involved in the process of Hypertension. The results suggest that the extract mainly alter the metabolic pathways of amino acid in Dahl salt-sensitive rats and its antioxidant potential reduced the hypertension patterns of Salt-sensitive rat. The antihypertensive components malic acid, aspartic acid, and glycine of extract can be used as therapeutic drugs to protect kidneys from salt-induced hypertension. PRACTICAL APPLICATIONS: Hypertension is a multifactorial disease and one of the risk factors for heart and kidney failure. Benincasa hispida is a widely used vegetable in China, which belongs to the Cucurbitaceae family. Benincasa hispida (wax gourd) has been used in traditional Chinese medicine for the treatment of inflammation and hypertension. The Benincasa hispida contains many compounds such as amino acids, carbohydrates, volatile compounds, vitamins, and minerals. The amino acid present in the pulp of Benincasa hispida are ornithine, threonine, aspartate, glutamate, serine, glycine, proline, alanine, valine, cysteine, isoleucine, tyrosine, leucine, lysine, phenylalanine, histidine, arginine, and γ-aminobutyric acid. Our results showed that Benincasa hispida is one of the potent natural antioxidants and can maintain normal blood pressure in Dahl salt-sensitive rats (D-SS). In conclusion, the current results provide good theoretical basis for the development and research using Benincasa hispida as an effective natural antioxidant for hypertension.

The Effects of Spironolactone in Preventing Bile Duct Ligation-induced Hepatitis in A Rat Model

Cholestasis is associated with the accumulation of bile acids and bilirubin in the hepatocytes and leads to liver injury. Pregnane X Receptor (PXR) coordinates protective hepatic responses to toxic stimuli, and this receptor was reported to stimulate bile secretion by increasing MRP2 expression. Since PXR activators were reported to be anti-inflammatory in the liver, PXR was proposed as a drug target for the treatment of chronic inflammatory liver diseases. We investigated the potential protective effect of spironolactone (SPL), an enzyme inducer, in hepatotoxicity induced by bile duct ligation in rats. Wistar Albino (250-300 g) rats were divided into the control group and the bile duct ligated (BDL) group. BDL group was divided into three subgroups; following BDL, for 3 days, the first group received propylene glycol (vehicle of SPL) (blinded), the second subgroup received spironolactone (SPL) (200 mg/kg oral), and the third subgroup received SPL for 3 days, starting 3 days after the bile duct ligation, in order to investigate if it has a healing effect after hepatitis had developed. The control group was sham-operated and received saline. At the end of the experiment, blood and tissue samples were collected. Serum TNF-α, NF-ĸB, bilirubin, IL-6 levels, ALT, AST, ALP activities and tissue MPO activity and oxidant damage increased after the bile duct ligation was significantly decreased following SPL administration. PXR and MRP2 activity showed an increase in the hepatocytes as a result of the treatment. In conclusion, it was observed that SPL administration significantly decreases liver inflammation and damage related to BDL.

Nicorandil and atorvastatin attenuate carbon tetrachloride - induced liver fibrosis in rats

PURPOSE

The present study aimed to evaluate the possible hepatoprotective effects of nicorandil and atorvastatin against experimentally induced liver fibrosis.

MATERIALS AND METHODS

Wistar male rats wereassigned tofivegroups; control group, fibrosis group, the remaining three groups received in addition to CCl₄, N-acetyl cysteine (300 mg/kg), nicorandil(15 mg/kg) and atorvastatin (20 mg/kg), respectively. Liver fibrosis was induced by intraperitoneal injection of rats with CCl₄ (2 ml/kg), twice weekly for five consecutive weeks. All treatments were administered daily starting from the first day of fibrosis induction for five consecutive weeks. By the end of the experiment, fibrosis biomarkers [hepatic transforming growth factor β1 (TGF-β₁) and hydroxyproline (HYP)], liver function [serum alanine transaminase (ALT), aspartate transaminase (AST), albumin and total bilirubin] were assessed. Moreover, lipid profile [total cholesterol, serum triglycerides, high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C)], inflammatory biomarkers [hepatic myeloperoxidase (MPO), serum tumor necrosis factor alpha (TNF-α)], relative liver weight] and oxidative stress biomarkers [malondialdehyde (MDA), glutathione (GSH) and catalase (CAT)] were evaluated. In support, histopathological and immunohistochemical examination of liver alpha smooth muscle actin (α-SMA) were performed.

RESULTS

Nicorandil and atorvastatin effectively reduced fibrosis and liver function biomarkers. They both restored serum lipid profile, TNF-α, MPO, relative liver weight, and hepatic MDA content. Alternatively, they markedly elevated albumin, HDL-C and hepatic content of GSH and CAT. Additionally, a marked histopathological and immunohistochemical improvement of α-SMA was observed.

CONCLUSION

Nicorandil and atorvastatin might be promising protective agents against liver fibrosis through amelioration of liver function, modulation of fibrous formation, anti-inflammatory and antioxidant potentials.

Nicorandil prevents the nephrotoxic effect of cyclosporine-A in albino rats through modulation of HIF-1α/VEGF/eNOS signaling

Despite that cyclosporine-A (CsA) is a widely used immunosuppressive drug, its nephrotoxic effect limits its long-term administration. Herein we tried to investigate its renal effect on endothelial dysfunction targeting the hypoxia-inducible factor (HIF-1α) / vascular endothelial growth factor (VEGF) / endothelial nitric oxide synthase (eNOS) pathway and the possible modulation by nicorandil. Eight groups of adult male Wistar rats were included: (1) control; (2) vehicle group (received oil); (3) glibenclamide 5 mg·kg^-1·day^-1 administered orally; (4) nicorandil 10 mg·kg^-1·day^-1 administered orally; (5) CsA 25 mg·kg^-1·day^-1 administered orally; (6) combined administration of CsA and nicorandil; (7) glibenclamide was added to CsA; and (8) both CsA and nicorandil were combined with glibenclamide. The treatment continued for six weeks. Combined nicorandil with CsA improved renal function deterioration initiated by CsA. CsA decreased the renal expression levels (P < 0.001) of HIF-1α, eNOS, and VEGF, inducing endothelial dysfunction and triggering inflammation, and upregulated the profibrotic marker transforming growth factor (TGF-β). Nicorandil fixed the disturbed HIF-1α/VEGF/eNOS signaling. Nicorandil corrected the renal functions, confirmed by the improved histological glomerular tuft retraction that was obvious in the CsA group, without significant influence by glibenclamide. Proper protection from CsA-induced nephrotoxicity was achieved by nicorandil. Nicorandil reversed the disturbed HIF-1α/VEGF/eNOS pathway created by CsA.

Role of nitric oxide donor in methotrexate-induced testicular injury via modulation of pro-inflammatory mediators, eNOS and P-glycoprotein

Methotrexate (MTX) is a widely used chemotherapeutic agent but its clinical use is challenged with different forms of toxicities including testicular injury. The aim of the current study was to evaluate the potential protective effect of potassium channel opener, nicorandil (NIC) (3 and 10 mg/kg/day) on MTX-induced testicular injury in a rat model. Rats were randomly divided into four groups (nine rats each) and treated for 2 weeks as follows: (I) normal control (CON group) received vehicle, (II) model group (MTX group) given MTX (20 mg/kg) single intraperitoneal (i.p.) injection dose on 11th day, (III) MTX + NLD group treated with NIC (3 mg/kg/day) orally for 2 weeks and MTX (20 mg/kg) single i.p. dose on 11th day, and (IV) MTX + NHD group treated with NIC (10 mg/kg/day) orally for 2 weeks and MTX (20 mg/kg) single i.p. injection on the 11th day. The testicular injury was assessed biochemically via serum testosterone, total antioxidant capacity, testicular oxidative stress parameters, P-glycoprotein, tumor necrosis factor-alpha, and interleukin-1β. Furthermore, histopathological evaluation, endothelial nitric oxide synthase (eNOS) immunoexpression, and detection of p53 expression level using Western blotting were performed. Results showed that MTX induced testicular injury which was proved by both biochemical and histopathological evaluations. Our results concluded that NIC pretreatment attenuated MTX-induced testicular injury via significantly increased eNOS immunoexpression, antiapoptotic, anti-inflammatory, and antioxidant properties. Interestingly, NIC high dose is more protective than low dose.

Correction of retinal ischemic injuries by using non-selective imidazoline receptor agonists in the experiment

Introduction: Retinoprotective effects of non-selective imidazoline receptor agonists: potassium salt of С7070; sodium salt of С7070; С7070 processed with CO2 – were investigated in comparison with C7070 on the retinal ischemia-reperfusion model in rats.

Materials and methods: The protective effects of the substances were evaluated by using ophthalmoscopy, laser Doppler flowmetry, electroretinography, histological and morphometric studies of retinal layers.

Results and discussion: The most pronounced retinoprotective effect was observed in potassium salt of C7070 at a dose of 10 mg/kg, which expresses in approaching the normal eye fundus image, achieving the target values of the retinal blood flow, b/a coefficient, and reaching the norm values of morphometric indicators. A less pronounced protective effect was found in sodium salt of C7070 at a dose of 10 mg/kg, which expresses in a 71% decrease (p &lt; 0.05) in semi-quantitative assessment of the eye fundus changes, an increase in the retinal blood flow level by 70.4% (p &lt; 0.05), in b/a by 94% (p &lt; 0.05) in comparison with the group without correction, and reaching the norm of the morphometric indicators. A retinoprotective effect of the substance C7070 processed with CO2 at a dose of 10 mg/kg is inferior to that of the sodium salt of C7070.

Conclusion: The retinoprotective activity of the substances is expressed in descending order: potassium salt of С7070 (10 mg/kg) ≈ С7070 (50 mg/kg) &gt; sodium salt of С7070 (10 mg/kg) &gt; С7070 processed with CO2 (10 mg/kg) ≈ С7070 (10 mg/kg). Injections of glibenclamide leveled the neuroretinoprotective effects of the substances to varying degrees, which confirmed the participation of ATP-dependent potassium channels in the implementation of these effects.

Nicorandil: A drug with ongoing benefits and different mechanisms in various diseased conditions

Nicorandil is a well-known antianginal agent, which has been recommended as one of the second-line treatments for chronic stable angina as justified by the European guidelines. It shows an efficacy equivalent to that of classic antianginal agents. Nicorandil has also been applied clinically in various cardiovascular diseases such as variant or unstable angina and reperfusion-induced damage following coronary angioplasty or thrombolysis. Different mechanisms have been involved in the protective effects of nicorandil in various diseases through either opening of adenosine triphosphate-sensitive potassium (KATP) channel or donation of nitric oxide (NO). The predominance or participation of any of these proposed mechanisms depends on the dose of nicorandil used, the location of diseased conditions, and if this mechanism is still functioning or not. The protection afforded by nicorandil has been shown to be mainly attributed to KATP channel opening in experimental models of myocardial and pulmonary fibrosis as well as renal injury or glomerulonephritis, whereas NO donation predominates as a mechanism of protection in hepatic fibrosis and inflammatory bowel diseases. Therefore, in different diseased conditions, it is important to know which mechanism plays the major role in nicorandil-induced curative or protective effects. This can bring new insights into the proper use of selected medication and its recommended dose for targeting certain disease.

Hydrogen sulfide modulates IL-6/STAT3 pathway and inhibits oxidative stress, inflammation, and apoptosis in rat model of methotrexate hepatotoxicity

Methotrexate (MTX) is a commonly used anticancer and immunosuppressive agent. However, MTX can induce hepatotoxicity due to oxidative stress, inflammation, and apoptosis. Hydrogen sulfide (H₂S), the endogenous gaseous molecule, has antioxidant, anti-inflammatory, and anti-apoptotic effects. The present work explored the probable protective effect of H₂S against MTX hepatotoxicity in rats and also the possible mechanisms underlying this effect. MTX was given at a single intraperitoneal (i.p.) dose of 20 mg/kg. Sodium H₂S (56 µmol /kg/day, i.p.), as H₂S donor, was given for 10 days, starting 6 days before MTX administration. H₂S significantly reduced serum alanine aminotransferase, hepatic malondialdehyde, interleukin 6, nuclear factor κB p65, cytosolic cytochrome c, phosphorylated signal transducer and activator of transcription 3, and Bax/Bcl-2 ratio and significantly increased hepatic total antioxidant capacity and endothelial nitric oxide synthase (eNOS) in rats received MTX. In addition, H₂S minimized the histopathological injury and significantly decreased the expression of STAT3 in liver tissue of MTX-challenged rats. The effects of H₂S were significantly antagonized by administration of glibenclamide as K_ATP channel blocker, Nω-nitro-l-arginine, as eNOS inhibitor, or ruthenium red, as transient receptor potential vanilloid 1 (TRPV1) antagonist. It was concluded that H₂S provided significant hepatoprotection in MTX-challenged rats through its antioxidant, anti-inflammatory, anti-apoptotic effects. These effects are most probably mediated by the ability of H₂S to act as IL-6/STAT3 pathway modulator, K_ATP channel opener, eNOS activator, and TRPV1 agonist.

Phosphodiestrase-1 and 4 inhibitors ameliorate liver fibrosis in rats: Modulation of cAMP/CREB/TLR4 inflammatory and fibrogenic pathways

BACKGROUND

Phosphodiestrase (PDE) enzymes are suggested to play a leading role in fibrogenesis of liver where studies showed the possible implication of PDE 1 & 4 in liver injury proposing them as possible targets for treating liver fibrosis.

AIM

The present study was designed to investigate, for the first time, the possible therapeutic effects of selective inhibitors of PDE-1 (vinpocetine) and PDE-4 (roflumilast) in liver fibrosis induced by diethylnitrosamine (DEN) in rats.

MAIN METHODS

Rats were given DEN (100 mg/kg, i.p.) once weekly for 6 weeks to induce liver fibrosis. Vinpocetine (10 mg/kg/day) or roflumilast (0.5 mg/kg/day) was then orally administered for 2 weeks.

KEY FINDINGS

Vinpocetine significantly suppressed the contents of hydroxyproline, transforming growth factor-beta 1 (TGF-β1), nuclear factor-kappa B (NF-κB) whereas roflumilast normalized them. Moreover, tumor necrosis factor-alpha (TNF-α) content and protein expressions of toll-like receptor 4 (TLR4) and tissue inhibitor of metalloproteinase-1 (TIMP-1) were markedly decreased whereas cAMP response element binding (CREB) protein expression was significantly elevated by both treatments. Additionally, vinpocetine and roflumilast up-regulated the gene expression of bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) receptor where roflumilast showed better results. PDE1 and 4 activities were inhibited by vinpocetine and roflumilast, respectively. The superior results offered by roflumilast could be related to the higher cAMP level obtained relative to vinpocetine.

SIGNIFICANCE

Our study manifested the up-regulation of PDE enzymes (1 & 4) in liver fibrosis and addressed the therapeutic role of vinpocetine and roflumilast as PDEIs through a cAMP-mediated TLR4 inflammatory and fibrogenic signaling pathways.

Interrelation of liver vascularity to non-alcoholic fatty liver through a comparative study of the vasodilator effect of carvedilol or nicorandil in rats

AIM

An experimental study of the effect of two vasodilators, carvedilol (B blocker with alpha-antagonist) and nicorandil (NO donor) on nonalcoholic fatty liver (NAFLD) induced by hypercholesterolemia and fatty diet in rats through studying the possible anti-inflammatory and antioxidant mechanisms.

MAIN METHODS

The rats were divided into 4 groups (6 rats each): The first (negative control group). The second, third and fourth groups were fed with cholesterol and fat- enriched diet for one month that stopped and continued on the standard diet for another month without treatment in the second group but treated with carvedilol and nicorandil in the third and fourth group respectively.

KEY FINDINGS

They revealed that both improved NAFLD especially nicorandil treated proved by the reduction of liver enzymes (AST, ALT), the fatty infiltration determined histologically and biochemically (decrease liver triglycerides). This may be due to either being antioxidants (reduced malondialdehyde and elevated reduced glutathione) or anti-inflammatory (decreased of TNF-α) together with the reduction of insulin resistance and adiponectin elevation or gene expression (increased liver NF-κB and decreased eNOS expression) and finally maybe by their obvious effect on improvements of lipid parameters.

SIGNIFICANCE

Carvedilol and nicorandil improved NAFLD through the interrelationship between inflammatory cytokines, antioxidants and insulin resistance.

Tissue-specific effects of targeted mutation of Mir29b1 in rats

BACKGROUND

miR-29 is a master regulator of extracellular matrix genes, but conflicting data on its anti-fibrotic effect have been reported. miR-29 improves nitric oxide (NO) production in arterioles by targeting Lypla1. Mir29b1 targeted mutation exacerbates hypertension in a model derived from the Dahl salt-sensitive rat. We examined the effect of Mir29b1 mutation on tissue fibrosis and NO levels with a focus on kidney regions.

METHODS

Mir29b1 targeted mutant rats on the genetic background of SS-Chr13^BN rats were studied. Masson trichrome staining, molecular and biochemical assays, metabolic cage studies, and bioinformatic analysis of human genomic data were performed.

FINDINGS

The abundance of miR-29b and the co-transcribed miR-29a was substantially lower in mutant rats. Tissue fibrosis was significantly increased in the renal outer medulla, but not in the renal cortex, heart or liver in mutant rats on a 0.4% NaCl diet. Lypla1 protein abundance was significantly higher and NO levels lower in the renal outer medulla, but not in the renal cortex. After 14 days of a 4% NaCl diet, 24 h urine volume and urinary sodium excretion was significantly lower in mutant rats, and tissue fibrosis became higher in the heart. NO levels were lower in the renal outer medulla and heart, but not in the renal cortex. Human miR-29 genes are located in proximity with blood pressure-associated single nucleotide polymorphisms.

INTERPRETATION

The renal outer medulla might be particularly susceptible to the injurious effects of a miR-29 insufficiency, which might contribute to the development of hypertension in Mir29b1 mutant rats.